Velocity fluid vacuum seal, method, and apparatus



Aug. 10 ,D 1926. 1,595,482

O. MINTON VELOCITY FLUID VACUUM SEAL, METHOD: AND APPARATUS Original Filed-Jan. 2o, `1922 A TORN Y Patented Aug. 1o, 1926.

UNITED STATES PATENTOFFICE.

OGDEN MINTON, OF GREENWICH, CONNECTICUT. l

VELOCITY FLUID VACUUM SEAL, METHOD, v.AND AIPPARA'IUS.

Application filed January 20, 1922, SerialV No. 530,667. Renewed February 17, 1926.

My `present invention is covered broadly 1n my. companion application Ser.4 No. 421,-

436 filed Nov. 30, 192() and my companion application Ser. No. 530,990, filed January 2l, 1922; this application being a species of the genus disclosed and claimed in said cases.

My invent-ion relates to the method of treating` materials in a vacuum, and more particularly to the method of protecting the opening or 'openings into the vacuum chamber, through which opening or openings the material to be treated is introduced and withdrawn 'from the chamber.

Myinvention relates more particularly to a yvacuum seal maintanied by the appllcation .of velocity head, i. c. the difference in pres- Y'sure between the atmosphere and vacuum be` ing balanced by the velocity head of the sealing medium.v Through this seal the materialto be treated in the vacuum chamber cis assed in any suitable manner.

ily invention further relates more particularly to the method of drying sheet material, as a continuous web of paper either material to be. treated is introduced and withdrawn through said seals.

My present invention relates to employing water, or other similar fluid having an affinity for the material being treated, as the fluid of the velocity seals, or any other suitable sealingliquid ,Whether it has an affinity `forthe web or not.

My invention furthe-r relates to employing passages having restricted -areas merging into progressively larger areas between the atmosphere and the. interior of the vacuum chamber, forming in effect Venturi nozzles, 'through which the fluid of the velocity fluid seals flows and the web passes.

Mv invention more particularly relates to employing fountains of sealing liquid at the entrance and exit passagesto guard said passages against the admission of air into the .vacuum chamber. VThe flow of the liquid in these. fountains may just besuflicient to equal the pressure of the atmosphere, in

which case .the sealing liquid would have practically no ilow. Preferably the flow of the sealing liquid in the fountains is a little greater than that necessary to balance atmospheric pressure, in which case there will be a bubbling of the liquid out of the re,- stricted passage of vthe fountain, the liquid preferably being caught in catch basins.

My invention vfurther relates to certain steps, and combinations of steps, also. to eertain elements and combinations o'f elements, whereby the method or processes herein described may be carried out, as well as to certain details oi construction, all of which will be more fully hereinafter described in the specification and lpointed out in the claims.

I have shown in the drawings, one form oi apparatus which may be used to carry out my improved method, ybut it is to be distinctly understood that my invention is not to be confined to thel particular form of apparatus, shown by way of illustration.

In the accompanying drawings the same reference numerals refer to similar parts in the several figures.

Fig. l is a vertical diagrammatic View oi one form of my invention;

Fig. 2 is atransverse vertical section through the web and the Vupper and lower carrier belts.

The vacuum chamber A has a vacuum maintained therein in any suitable manner by connecting the pipes l, l with any suitable exhausting apparatus. This vacuum chamber has two passages 9 2 open to the atmosphere. Through these passages the material to be treated in the vacuum chamber A is introduced and withdrawn. Of course if the passages were left unguarded the vacuum inthe vacuum chamber A would be broken.

My invention consists in guarding these passages 2, z2 from the atmosphere by fountains o sealing fluid, the fluid having an atlinity for the web treated; or the sealing fluid may have no ainity Jfor the web treated, such,fluidsffoiexample, as mercury, amalgam-.oranysumlarsubstance.

The.web is then fed continuously, 4with its surrounding and protecting waterproof car- I have shown the continuous web 3 of rier belts 13 and 15, through the entrance paper coming either. from thefwet enelA of 'a paper machine,l or from a sizing vat, or from ay coloring" apparatus, printing machine, coating machine'or directly from aroll .of Wet paper. This web -passes into the vacuum chamber A through theprestricted passage 2 guarded b the entrance fountain 4. The. sealing liqui 5 is caused to move 1n the fountainand pass through the restricted Anozzle 6 into the progressively larger por-4 tion 7. Whatever velocity the liquid may have as it passes through the Venturi nozzle 6, its velocity Will be reduced as it passes into the enlarged portion 7. 'The' velocity, of this sealing liquidmust be such that it exerts a pressure which will equal the pressure of the outside atmosphere. I have .shown my fountain 4 provided with two rotary pumps 9, 9, which propel the sealing fluid through the restricted passage 6 in the direction of the enlarged opening 7. For

economy of operation, the speed of the rotary pumps 9, 9 should just be sullieient to cause the moving sealing liquid 5 to exert a pressure which will equal -the atmospheric pressure, in which case, if maintained, there would be practically no movement or eircul lation of the sealing liquid. In practice` however,'I preferably run the rotary pumps 9, 9 sothat the moving liquid of the seal will have just sufficient velocity to slightly overcome the pressure of the atmosphere, causing the sealing liquid ,to bubble or llow over the lip 10, and into the catch basin 11. lVhen the catch basin is full of sealing liquid the excess may be permitted to run to waste, or, it may be led by the pipe 12 back to the pumps 9, 9, so that it may be used over and over again. rlhe rotary pumps revolve at such a speed and in such a direction that they throw the liquid of the seal towards the restricted passage G and away from the slot 45 so that no sealing liquid will pass through said slot into the vacuum chamber A.

The fountain 4 guarding the exit' passage 2 of the vacuum chamber, is the same as that just described.

When the sealing liquid is water or any suitable liquid that has an atlinity for the web 3 of paper or similar material. l provide means to protect the web from contact with the sealing liquid when it passes through the fountains guarding` the entrance and exit of the Vacuum chamber. I may, for example,

vas shown in Fig. l, use an upper carrier belt 13 passing over the guide roll 1J.. where it meets the web 3 and the lower earner belt l5, as it passes over its own guide roll lt. These upper and lower guide belts 13 and 15 are formed of some waterproof material and are wider than the web 3 and thoroughly protect it as shown for example in Fig. Q.

fountain 4 and into the 'vacuum chamber A.. As-soon. as the carrier beltsl and 15 are ,welll 4Within the vacuum chamber, I separate 4where it again meets the web of paper, now

dry, and passes with it and the upper Car- 'rier belt 13 through the lexit fountain 4. The lower carrier belt is caused to move continuously over the guide rolls 29, 30, 31, 32, and 33 back to the guide roll 16. The upper carrier belt 13 is likewise caused to move continuously over the guide rolls 34, 35, and 3G back to the guide roll 14.

It is found in practice that the shrinkage of the web 3 upon the ditferent drying drums or cylinders il?, 3S, '39, 40 and 41 is unequal. I, therefore, provide separate and individual felts 42, 42 for each one of the drying drums` of cylinders 3T, 3S, 39, 40 and 41, the fclts passing continuously over their respective guide rolls 43, 43.

My invention is particularly adapted to be used in connection with drying sheet material in the form of paper, though it is to be distinctly understood that it is equally applicable to and covers drying sheet material in the form of textile fabrics, as for example, drying such fabrics after they have been washed or bleached or dyed, or otherwise treated by a liquid of some description.

ll'hile I preferably use the same liquid in each of the fountains 4, 4, I may, of course,

use one liquid in one fountain and a ditlcrent sealing liquid in the other.

My method possesses many advantages not present in proce ses heretofore used for many years in the drying of paper.

'lfhe evaporation process, which is characteristic of the :so-called loft drying of paper, has many fully recognized disadvantages, and yet it is used today and has been in use for many years. paper is taken from the paper machine, cut into sheets, hung on poles, carried to the drying room where it is subjected to hot air at about 1390 F. for about l5 hours. and when dry, each sheet is sepa ately calendered. Although posscssing the advantage of drying at a comparatively low temperature, whereby the moisture slowly evaporated, loft drying is obviously very inetlicient and costly, because it requires many separate ina-- nipulations, is extremely slow, uses extensive floor space and wastes heat.

The process which is employed in the ordinary paper machine in common use, is likewise subject to many disadvantages. In such machine, the wet paper as, it comes from the paper machine, is passed over ma nv In this method the wet` Urevolvng c linders, heated internally by steam to su ciently high degree-.of heat, to

raise the temperature of the Water in the paper to 212 F., the atmospheric boiling point of water. It is customary to supply vthe drying cylinders with steam at approxi` mately 5.3 pounds gauge pressure, at which the steam has a temperature of 228o F., gi`ving a difference of temperature (228-212) ehines often one hundred, and in news print machines, forty or more.

Also due to convection and conduction losses, as well as those incident to leaks in the piping system and other inefliciencies,` the heat actually required for atmospheric drying 'of a ton of wet paper, is very much in excess of the theoretical requirement. The thermal elliciency ot' atmospheric drying hy'steam heated cylinders is therefore very low.. Furthermore, the vapor produced from boiling the water out of the paper, is driven oft' into the operating room, and although fans and exhausters are employed, at large expense for power and maintenance, the room atmosphere is so constantly satuvr ated with moisture as to rust and ultimately destroy all iron andv steel materials, and

produces an exceedingly disagreeable and unhealthy atmosphere 1n winch to work.` It

is well known that the minimum temperature 212, the atmosphericboiling point of water, positively injurious to, and results in oxidizing, the libres of the paper, the strength of which is vastly improved when the paper is dried at lower temperatures, as lin loft drying. This atmospheric drying process.requires large initial cost for cylinders, felts, and other necessary equipment, and extensive floor space, and results in the consumption of large amounts of power, and great cost for operation, maintenance and repairs.

In my improved vacuum drying methodI vcontemplate maintaining within the chamber a vacuum of about 28". of mercury, in which water boils at 100 F., and supplying the 'drying cylinders with steam at 5.3 pounds gauge pressure, producing a temperature of 228 F. The temperature dify:ference between the ten'iperature of the steam in the cylinders and that of the paper, is therefore, 128 F. in my vacuum method, or 8 times greater (16 F. 8:128 F.) than the temperature diierence in atmos` pheric drying. In my improve1 method the paper dries approxin'iately 8 times faster than in atmospheric drying, and I require only about one-eighth the number of drying cylinders to dry paper at the same rate speed. I ain-able to dry paper with 5 cylin ders in the same time required oi'l 40 cylinders drying at atmospheric pressure, resulting in eat economies in cost of the machl-ne,y oor space and of necessary piping, `felts, auxiliary equipment, land particularly `inlpower and maintenance charges.

The thermal' eliciency of my vacuum method is very much greater than that of the atmospheric cylinder drying heretofore in universal' use for drying paper. Theoretically, it frequire's about 4287 pounds of steam to dry one ton of paperat atmospher ic pressure, but to compensate for convection andv conduction losses, and those due to leaks in the piping system, and other inetlii ciencies, it vhas been shown in practice that about 10,000 pounds are required.

In my method, using a vacuum of about" 28, the convection, conduction and piping losses are exceedingly small and the total steam required to dry a ton of paper by my method is approximately 5200 pounds.

It is an established fact that paper dried at low temperatures is much stronger than when it is dried at the high temperatures 'used in paper machine atinospheric drying.

Paper dried in" a vacuum of 28, 0r at a temperature of about 100 F. as in my method, is Very much stronger than paper dried at atmospheric pressure, when the steam in the driers is at 228 F. W'hen paper is dried by my method, therefore,l a cheaper furnish or stock can be used and still produce a paper equal in strength to atmospheric dried paper, in which a higher grade furnish or stock is used. In making newsprint paper, I amable to dispense with a considerable portion of 'the more expensive sulphite pulp, as this can be replaced with the cheaper groundwood pulp. By my method I also reduce the number of breaksin the web as it passes over the cylinders. y

Furthermore, in my method there is' a great saving of heat (or steam) because thesteam, humidity and heat, and fans, and exhausters are dispensed with. In the use of my method the apparatus is at 'all times operating under definite humidity, the` coutrol ot the drying can be closely standard ized, and the moisture content in the paper carefully regulated.

Some of the modern open air dryers are equipped with a blower system by which air, either heated or not, is blown through the dryer section. uhich will lower the temper ature at which the water'is evaporated from the paper much below 212 F. and may, in some cases, reduce the temperature of evaporation as low as 180 F. or lower.

iso

Having pointed out the many advantages of ,iny 4iiietliod-andapparatus -over those heretofore used, it will be apparent that the use of my invention results in great economyV 5 inthe initial cost ofapparatus andi-n large savings in cost of' operation, maintenance' and repairs. l i I y -Having thus described this linvention in connection with an illustrative embodiment l0 thereof,.to`the details of whicl'I do not de-l sire to be limited, what'is claimed'as" new and what is desiredt-o secure by Letters Patent is set forth in the appended claims.

What I 'cl`aiin.is:- 1 'A 1. The method of sealing a vacuum chamber having openings for the admissin and withdrawal of material into and from said.

` vacuum chamber consisting -in propelling a sealing'liquid'through the openings against ressu're yof the atmosphere and with sufficient force to exceed the pressure of the atmosphereto prevent air working into the vacuum chamber.

2. The i'nethod of drying a web of paper or-.other sheet materalconsisting in passing it into'and out of a `vacuum chamber through entrance and exit passages opening upwardly, and through a sealing liquid propelled in a substantially vertical direction and with Vsufficient velocity to exceed the pressure of the atmosphere and drying the Web of paper in the vacuum chamber.

3. The method of drying anveb of paper ,or other sheet material consisting in passing 35 it into and out of a vacuuinchamber through entrance and eXit passages opening up-` wardly, and through Water mounted in said passages and propelled in a substantially vertical direction and with suiiicient velocity 10. to exceed the pressure of the atmosphere and protecting the web from contact with the water and drying the web of paper in the vacuum chamber.

4. In, a vacuum apparatus provided with entrance and exit passages opening upwardly for the continuous passage of a web of Sheet material, fountains protecting the entrance and eXit passages, said fountains (being provided with passages for the web of `sheet material,A a. sealing liquid in the fountains, and means to cause the liquid to move With sutiicient velocity to obtain a pressure slightly exceeding that of the atmosphere to prevent'air Working into the vacuum cham- -ber.

5. ln a vacuum apparatus provided with entrance and exit passages opening upwardly for the continuous passage of a web of sheet material, fountains protecting l:he entrance and exit passages, said fountains being provided With passages for the web of sheet material, a sealing liquid in the fountains, and means to cause the liquid to move with suflicient velocity to obtain a pressure slightly exceeding that of the atmosphere to .sheet material, a sealing liquid in the fountains, and ineans'to cause -tlieliquid to move with suiiicient velocity to obtain a pressure slightly exceeding that of the atmosphere to prevent air working into the vacuuni chamber, and upper and lower carrier belts to prevent the liquid of the seal contacting with the web.

7. In a vacuum apparatus provided with entrance and exitpassages opening upwardly for the continuous passage of a web of paper, fountains including rotary pumps located in and guarding the entrance and exit passages, and a sealing iiuid in said fouiitains.

8. In a vacuum apparatus provided with entrance and exit passages opening upwardly for the continuous passage of a web of paper, fountains including rotary pumps located in and guarding the entrance and exit passages, and water in said fountains.

9. 'In a vacuum apparatus provided with 'entrance and exit passages opening upwardly for the continuous passage of a web ot paper, fountains including rotaryv pumps located in and guarding the entrance and exit passages, a sealing tiuid in said fountains, land a catch basin and means to lead the overflow liquid back to the rotary pumps.

l0. The combination in a vacuuin apparatus of one or more fountains guarding passages opening upwardly into the vacuum chamber, each fountain provided with u passage for the material to be treated and having pumping means located in the passages adapted to propel a sealing liquid in the directi'on of the atmosphere and at sullicient velocity-to obtain a pressure exceeding the pressureof the'atniosphere, and said sealing fluid. Y

ll. The combination in a vacuuin apparatus of one or more fountains guarding passages opening upwardly into the vucuuni chamber, each fountain provided with a passage for the material to be treated und having pumping means located in the passages and adapted to `propel a sealing liquid in the direction of the atmosphere and at sullicient velocity to obtain a pressure exceciiling the pressure of the atmosphere, and said sealing fluid having an ailinity for the niaterial treated.

l2. The combination in a vacuum apparatus of vone or morev fountains guarding passages opening upwardly into the vacuum chamber, each fountain provided with apasllill llt) sage for the material to be treated and liav- Y terial treated, and means to protect the. ma-

terial treated from Contact with said sealing liquid.

13. The Combination in a vacuum apparatus ot one or more fountains'guardingr passages opening;n upwardly into the vacuum Chamber, each fountain provided with a passage for' the material to be treated and having pumping;r means located in the passages adapted to propel 4a sealing liquid in the di reetion of the atmosphere and at sullieient velocity to obtain a pressure exeeedinglthe pressureA ot' the atinosphere, and water as the sealingliquid.

14. The Vmethod of sealing a vacuum chamber provided with entraln'e and exit passages opening' upwardly, consisting in closing said passages with a sealing liquid.

which hy gravity supplemented by atmospheric pressure and the Vacuum ot the cham ber tends to t'oree the liquid into the vacuum ehan'iher, and balancing these eon'ihinerl forces so that the sealing liquid continues to seal the entrance and exit passages.

OGDEN'MINTON. 

